1. Field of the Invention
The present invention relates generally to the field of rig mats, and more specifically, to a rig mat with an interlocking mechanism that is superior to prior art because it prevents the accumulation of dirt, debris and frozen matter, has no parts that are easily bent or broken, and does not require manual assembly.
2. Description of the Related Art
Existing interlocking rig mat designs such as those described in U.S. Pat. No. 8,096,728 (Stasiewich et al., 2012), U.S. Patent Application Pub. No. 2011/0299923 (Bleile et al.) and U.S. Patent Application Pub. No. 2012/0087725 (Bathelt) are inferior because they allow dirt, debris and frozen matter such as snow and ice to accumulate within the interlocking mechanism itself. It is both difficult and time-consuming to clean out the interlocking mechanism, which leads to increased operational costs. Furthermore, existing rig mat designs are constructed with parts that are easily damaged or bent. Some rig mats (examples of which are discussed below) contain parts or pins that must be twisted or inserted as the mats are laid down.
A primary object of the present invention is to provide an interlock system that is self-cleaning and that does not include any parts that can be damaged or bent. A further object of the present invention is to provide an interlocking rig mat assembly that does not require the manual manipulation of parts and that can be easily assembled in the field.
Discussed below are several additional examples of road or ground mats with configurations that are structurally dissimilar to the present invention. As far as the inventors are aware, there are no prior art examples of rig mats that are structurally similar to the present invention.
U.S. Pat. No. 140,835 (Kilburn, 1873) provides a pavement mat with beveled ends for placing the mats end-to-end and stacking the end of one mat on top of the end of another mat, such that the mats lie flat to create an extended flat surface. This invention does not include any mechanism by which the mats are actually locked together.
U.S. Pat. No. 3,851,989 (Peach, 1974) discloses an expansion joint for slabs of concrete roadways. Each end of the slab has a sloped end that corresponds to the sloped end of the adjacent slab so that the end of one slab can be stacked on top of the end of another slab. The space between the sloped ends is sealed with hot asphalt. As with the previous patent, there is no mechanism for locking the concrete slabs together.
U.S. Pat. No. 7,025,530 (Beamish et al., 2006) and U.S. Pat. No. 7,160,055 (Beamish et al., 2007) both describe a road mat with a locking mechanism on either end of the mat. The locking mechanism consists of a male coupling and a female coupling on both ends of the mat. The female coupling is in the shape of a convex tube that extends along the entire width of the mat (either continuously or discontinuously and the male coupling is in the shape of a concave tube that extends along the entire width of the mat, such that the female coupling fits inside of the male coupling. The locking mechanism also includes supporting alignment plates that are situated between the female couplings on the ends of adjacent mats. This invention is problematic because its configuration allows dirt, debris and frozen matter to accumulate inside of the female couplings, and the male and female couplings are exposed to forces that may cause them to bend or break.
U.S. Pat. No. 7,604,431 (Fournier, 2009) provides an interlocking ground cover mat in which the ends of the mats are joined together with a retaining pin that feeds through openings in perpendicular plates. In an alternate embodiment, the ends of the mats are joined together by complementary pins and recesses. Both embodiments require the manual insertion of pins, and they present recesses in which dirt, debris and frozen matter may accumulate.
U.S. Pat. No. 7,934,885 (Fournier, 2011) discloses an interlocking ground cover mat similar in that described in U.S. Pat. No. 7,604,431 except that the ends of the mats incorporate an I-beam on one end and a tubular member on the other end. The tubular members fit inside of the I-beams, thereby securing the mats together. The ends of the tubular members are modified to facilitate insertion of a sling for lifting one or more mats and also to facilitate stacking of adjacent mats. This design suffers from the same disadvantages as the '431 patent.
U.S. Patent Application Pub. No. 2010/0200187 (Rolland et al.) describes an interlocking mat system in which the end of one mat slides laterally onto the end of another mat. The interlocking ends of the mats are comprised of tubular members formed of steel pipe with slots in them for slidably receiving a key on the end of an adjacent mat. This particular invention is difficult to assemble because each mat must be carefully and precisely slid sideways onto an adjacent mat. The keys are also vulnerable to being damaged in the process.
None of the above mat systems provides the advantages of the present invention, namely: (a) the automatic prevention of buildup of dirt, debris and frozen matter within the interlocking mechanism; (b) the elimination of any parts that can be damaged or bent during installation or use of the mat; and (c) the omission of any components that require manual manipulation in connection with installation or use of the mat. Furthermore, unlike the present invention, the prior art rigs mats discussed above require a separate ramp to be placed onto the end of the mat in order to drive a vehicle up onto the mat; this disadvantage is overcome by the present invention. These and other structural features of the present invention are discussed more fully below.